This invention relates to means for controlling the floor-level cutters of a coal plough.
DT-OS 2,250,535 describes a coal plough having two sets of floor-level cutters mounted on respective carriers at the two ends of the plough, one set of cutters being operative for each direction of plough travel. Each carrier can be pivoted between a working position, in which its cutters are operative, and a non-working position, in which its cutters are not operative. Thus, the floor-level cutters which are not operative, in each direction of plough travel, can be pivoted upwardly out of contact with the floor of the mine working so as to reduce the rate at which they wear. The distance through which each carrier can pivot towards the floor is limited by means of an adjustable stop constituted by a pin which is insertable into any one of a plurality of holes formed in the plough body. Pivoting in the other (upward) direction is limited by a fixed stop provided on the plough body. The disadvantage of this type of plough is that, when the direction of plough travel is changed, the floor level cutters previously inoperative cannot be guaranteed to pivot into their working positions, and the cutters previously operative cannot be guaranteed to pivot into their working positions.
DT-AS 2,340,302 discloses a coal plough whose main cutters are pivoted into, and out of, working positions by control means engageable with the coal face. Unfortunately, this type of control means is not suitable for controlling floor-level cutters.